Protecting-hood for thermo-couples.



A. F. MITCHELL. PROTECTING HOOD FOR THERMO-COUPLES.

APPLICATION FILED JUNE 23. I9I4.

Patented May 25, 1915.

.r IIIIIIII!IIIIIIII Z Z I. VENTOR r. MITCHELL, or nomnsrmn,PENNSYLVANIA.

PROTECTING-HOOD FOB THERIMO-GO'III'I'LES.

Specification of Letters Patent.

Patented May 25, 1915.

i Application filed June 23,1914. Serial No.- 846,716.

and while not restricted to such use more particularly relates to theconstruction of the hot end of thermo-couples forming part of electricpyrometers, used in determining the temperature of armor plates andsimilar metal bodies while such plates are being heated within afurnace.

Heretofore it has been the practice to in case the hot end of thethermo-couple within a cover made of iron', quartz, porcelain or similarheat resisting material, the covering being employed to preventoxidation of the is brought iii-contact with the article whose.

the pyrometer.

thermo-couple and the thermo-couple, of course, being connected bysuitably insulated wires to the galvanometer forming part of thepyrometer. It has also been the practice heretofore to use the apparatusby placing the naked or uncovered hot end of the thermo-couple incontact with the plate or other article, of which the tem erature is tobe determined, the cold end 0 the thermocouple b connected by suitablyinsulated wires to the galvanometer forming part of When used in thismanner, the hot end of the thermo-couple is subj ect to the heatinginfluence of the gases or' products of combustion passing throu h thefurnace, while the reading is being ta on and is also subjected to thecooling influence of the furnace bottom when applied to the under sideof the plate or other metal body, both influences acting to make thereadings inaccurate.

One object of my invention is to provide a thermo-couple having novelmeans whereby the hot end thereof is protected or insulated from thedirect action of the highly heated gases of the furnace. 7 V.

Another object of my invention is to provide a thermo-couple having-novel means whereby the hot end of the thermo-couple temperature is tobe measured while excluding it from the highlyheated atmosphere of theinterior of the furnace in which the plates or other articles aresituated.

Still further objects of my invention will become apparent hereinafteras the invention is more fully described and specifically pointed out inthe appended claims.

My invention. consists in a protecting hood, which surrounds thethermo-couple and hasan open side which enables the thermo-couple beingbrought and held in di-' rect contact with the heated article, while itstemperature is being determined and thereby excluding the thermo-couplefrom the action of the highly heated gases passing through the furnace.

Referring now to the drawings forming part of this specification, Figure1 is a longitudinal sectional side elevation of a heating furnace forheating armor plates and similar large metal bodies. Fig. 2 is alongitudinal section showing on a larger scale, the construction of theprotecting hood and the manner of applying the hood for use on the hotend of the thermo-couple in accordance with my invention. Fig. 3 is aninverted plan of the hood shown in Fig. Fig. 4 is an end elevation ofthe hood shown in Figs. 2 and'3.

'In the accompanying drawings, the numeral 2 indicates a heating furnacehaving an armor plate 3 mounted upon the supports 4 which are carriedupon the movable bottom 5jof the furnace, the plate being supported inthis manner to enable both sides to be simultaneously heated andobtain-a more uniform heating of the plates within the furnace.

The galvanometer 6 forming part of the electric pyrometer, is connectedby lead wires 7 and 8 to the hot end 9 of the thermo-couple and the hotend of the thermo-couple is positioned within the enveloping protectoror hood 10, forming a novel feature of this invention. The hot end 9 ofthe thermo-couple is conveniently bent to bring it into substantiallythe plane of'the side edges 11 of the open side of the protecting-hood10.

The rear end of the protecting hood is v I noineter, the Wires formingthe thermo-couple being of sufiicient. length to extend to the outsideof the furnace and the wires con-' veniently extending through thehollow handle 12. The wires within the pipe may be v covered with asuitable insulation as is insulating material. I mineral wool areother-insulating materials shown.

The interior of the hood 10 which is inclosed upon all but one of itssides is preferably filled with a suitable insulating ma-- terial 13forming a lining for the hood and assisting in maintaining the hot endof the thermo-couple in position within the protecting hood. Asbestospreferably is used as the Asbestos cement and by excluding suchatmosphere from contact with the hot end of the thermo-couple, and inthis way' the temperature readings are rendered much more accurate thanhas here;

tofore been possible with a paratus in which ing an open side enablingthe thermo-couple to contact directly with the surfaces of which thewires extend, forms a convenientwheated articles.

means for positioning the hot end of the thermo-couple in thedesiredlocation on the heated article within the furnace, it beinginserted within the furnace through suitable openings provided for thatpurpose in the side walls and in the doors or end walls of the furnace.

In placing the hot end of the-thermo-couple in position the side edges11.of the hood 10 come in contact with the surface of the plate, thetemperature of which is being measured, and in this way prevent thehighly heated gases in the furnace from coming into contact with thethermo-couple so that the heating action of the surface of the plate onthe hot end of the thermo-couple alone determines the registeredtemperature and inaccuracies heretofore present, due to the action ofthe gases, which are at a higher temperature than the heated metal, areprevented and avoided. The hot end 9 and its surrounding hood 10 areheld in direct contact with the surface of the plate 3 for the necessarytime interval and the temperature of the hot end of the thermo-couple,which will be the same as that of the temperature of the plate incontact therewith, is transmitted through the lead wires 7 and 8 to thegalvanometer and The advantages of my inventionwill be apparent to thoseskilled in the a-rtf" The use of my protecting hood prevents thetemperatures taken being influenced by the highly heated atmosphere ofthe furnace,

the temperature indicated on. the dial of the galvahometer.

2. In an electric pyrometera thermo-couple having lead wires and a hoodencircling the hot end of the thermo-couple, said hood having an openside enabling the thermo-couple to contact directly with the surfaces ofthe heated articles and an insulatin medium within the hollow protectinghood arranged to engage .with and hold the hot end of the thermo-couplein position within the protecting hood.

8. In an electric pyrometer a thermo-couple having lead wires and a hoodencircling the hot end of the thermo-couple, said hood hav ing an .openside enabling the thermo couple to contact directly with the surfaces ofheated articles and a handle secured to the protecting hood by which thehot end of the thermo-couple is manipulated.

4. In an electric pyrometer a thermo:couple having lead wires and a hoodencircling the hot end of the thermo-couple, said hood having an openside enabling the thermo-couple to contact directly with the surfacesofheated articles and a hollow handle secured to the protectinghood bywhich the hot end of the thermo-couple is manipulated, the leadiwiresfrom the hot end of the couple extending through said hollow handle.

In testimony whereof, I have hereunto

